COLOUR BIT DEPTH

“x-BIT” when used to describe a camera system refers to the colour BIT-DEPTH of either the internal processing or the output video format – they are not necessarily or even usually the same.

For instance most DSLRs have 14-BIT internal colour processing when grabbing image information from the sensor; this 14-BIT image is then compressed to an 8-BIT format that is saved as a video file by the camera.

The higher the BIT-DEPTH the greater the number of gradations between the 0% and 100% levels on a colour channel and hence the more subtle the tones.The human eye can detect approximately 10million distinct colours – fewer than that encoded even by 8-BIT colour systems (which, with 256 values for each colour channel, can encode 256x256x256 colours, more than 16million).

Despite this higher BIT-DEPTH systems are advantageous. The human eye is not equally sensitive throughout its dynamic range. The high BIT-DEPTH, linear, colour data from the sensor can be intelligently encoded in-camera or in post production to preserve the colour detail to which the eye is most sensitive- often by encoding in a logarithmic COLOUR SPACE, and using COLOUR SUBSAMPLING, and/or a BEYER MASK.